YVR - access D concourse with transborder boarding pass?
 

On my trip from YVR later this week, will they let me go through security to the international departures area (concourse D) with a USA boarding pass?

That is surely impossible. There is no access from international departures to US departures or to any other part of the airport.

Not a chance as you have to clear US Pre-Clearance to get to the USA departure gates. There is no possible way to do that coming from another concourse.

That's just not true, though. In May I arrived from Toronto, walked from the domestic gates to the international gates, just wandered around, used the international Plaza lounge, and then went into US preclearance without leaving security. There IS absolutely access.

Ah, that's interesting. I forgot there could be a connection path through the D gates from domestic to the US side. That leaves one question, which I took to be OP's question: would US passengers be admitted to the main entrance to the D gate area? That seems very unlikely to me, but maybe I'm wrong.

This is up to airport staff generally, I've heard of people getting it to work and others less lucky. If you're trying to enter a secure area without a valid (for that area) BP it's a very grey area ... It would be handy for those of us with lounge access only in domestic and TB areas but I can see reasons (one being extra traffic) why it's not technically allowed.

I mean imagine if everyone could go through security to see their friends and relations off. Would be chaos!

The international gate areas of YVR and YYZ have the additional complication of being TWOV areas, so there is no easy return to Canada.

How did you manage to exit the International concourse? Typically the only way to exit is for a staff member to lead you to Canada Border Services to have you processed through Canada Customs.

Passengers on arriving flights can make their way to US preclearance but I'm genuinely curious how you managed to go from wandering the duty free shops to accessing US preclearance?

Through the US Connections Facility. Basically there's an entrance from right behind the D-gate security that goes into the US Preclearance facility. You get there from Canada arrivals by walking through the long corridor that's shaded both blue and green (behind the int'l ticketing).

Connections Map - Canada Arrivals

Update: can confirm there's still access into preclearance from the D gates - I could see the passage - but they didn't let me into the D gate area with my E-gate boarding pass. Ah, well.